System and method for providing smart grid communications and management

ABSTRACT

A method is provided in one example embodiment and includes receiving a request for a service that involves phasor measurement unit (PMU) data; identifying a service device in a network to perform the service; and multicasting one or more results of the service to a group of subscribers identified by a multicast group address. In more particular embodiments, particular PMU data is redirected to the service device via a service insertion architecture (SIA) protocol. In addition, the service can include replicating packets and masking a subset of traffic for forwarding to a first hop router of the network. In certain example instances, metadata is used in order to apply the service to certain traffic propagating in the network.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority under 35 U.S.C. §119(e)to U.S. Provisional Application Ser. No. 61/390,099, “SYSTEM AND METHODFOR PROVIDING SMART GRID COMMUNICATIONS AND MANAGEMENT” filed Oct. 5,2010, which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

This disclosure relates in general to the field of energy and, moreparticularly, to providing smart grid communications and management.

BACKGROUND

Smart grid architectures have grown in complexity in recent years. Asmart grid can deliver electricity from suppliers to consumers usingdigital technology. The architecture can control appliances for businessand residential environments in order to conserve energy, reduce energycosts, and increase the reliability of energy delivery. In some cases, asmart grid can overlay an electrical grid, which has a metering system.Part of the smart grid is associated with applying, sensing, and/ormeasuring energy levels with two-way communications. Certain aspects ofthe smart grid can communicate information about grid conditions tosystem users and operators, which makes it possible to dynamicallyrespond to changes in grid conditions. Effectively managing energywithin network topologies presents a significant challenge to smart gridoperators, system designers, device manufacturers, government agencies,and service providers alike.

BRIEF DESCRIPTION OF THE DRAWINGS

To provide a more complete understanding of the present disclosure andfeatures and advantages thereof, reference is made to the followingdescription, taken in conjunction with the accompanying figures, whereinlike reference numerals represent like parts, in which:

FIG. 1A is a simplified partial block diagram illustrating a grid systemin accordance with one embodiment of the present disclosure;

FIG. 1B is a simplified partial block diagram illustrating possibleexample details associated with one embodiment of the presentdisclosure;

FIG. 1C-1 is a simplified partial block diagram illustrating possibleexample details associated with one embodiment of the presentdisclosure;

FIG. 1C-2 is a simplified partial block diagram illustrating possibleexample details associated with one embodiment of the presentdisclosure;

FIG. 2A is a simplified block diagram illustrating possible exampledetails associated with one embodiment of the present disclosure;

FIG. 2B is a simplified block diagram illustrating possible exampledetails associated with one embodiment of the present disclosure;

FIG. 2C-1 is a simplified partial block diagram illustrating possibleexample details associated with one embodiment of the presentdisclosure;

FIG. 2C-2 is a simplified partial block diagram illustrating possibleexample details associated with one embodiment of the presentdisclosure;

FIG. 2D is a simplified block diagram illustrating possible exampledetails associated with one embodiment of the present disclosure;

FIG. 2E is a simplified block diagram illustrating possible exampledetails associated with one embodiment of the present disclosure;

FIG. 2F is a simplified flow diagram illustrating potential operationsassociated with one embodiment of the present disclosure;

FIG. 2G is a simplified flow diagram illustrating potential operationsassociated with one embodiment of the present disclosure;

FIG. 2H is a simplified flow diagram illustrating potential operationsassociated with one embodiment of the present disclosure;

FIG. 3A is a simplified partial block diagram illustrating possibleexample details associated with one embodiment of the presentdisclosure;

FIG. 3B is a simplified flow diagram illustrating potential operationsassociated with one embodiment of the present disclosure;

FIG. 3C is a simplified flow diagram illustrating potential operationsassociated with one embodiment of the present disclosure; and

FIG. 4 is a simplified partial block diagram illustrating possibleexample details associated with one embodiment of the presentdisclosure.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS Overview MulticastTransmission

A method is provided in one example embodiment and includes receivingphasor measurement unit (PMU) data in a first transmission; convertingthe first transmission into a multicast transmission; and multicastingthe PMU data to a multicast group address, which identifies a pluralityof subscribers. In more specific implementations, the converting of thefirst transmission into the multicast transmission occurs at a first-hoprouter in relation to a PMU source that sent the first transmission. Insome cases, the first transmission is a unicast transmission sent from anetwork element, which includes a PMU sensor.

In yet other embodiments, the method may include adding a firstsubscriber to the multicast group address; and creating a new multicasttree based on the first subscriber. The method may also includemulticasting second PMU data over a second network to a secondsubscriber of a second multicast group address. An access control list(ACL) can be used to determine whether to forward packets associatedwith the PMU data, where the ACL is used for packet filtering in orderto permit or deny traffic forwarding to the multicast group address. Themethod may also include receiving second PMU data in a secondtransmission; combining the first transmission and the secondtransmission into a second multicast transmission; and multicasting thesecond multicast transmission to the multicast group address.

Virtualization of Services

A method is provided in one example embodiment and includes receiving arequest for a service that involves phasor measurement unit (PMU) data;identifying a service device in a network to perform the service; andmulticasting one or more results of the service to a group ofsubscribers identified by a multicast group address. In more particularembodiments, particular PMU data is redirected to the service device viaa service insertion architecture (SIA) protocol. In addition, theservice can include replicating packets and masking a subset of trafficfor forwarding to a first hop router of the network. In certain exampleinstances, metadata is used in order to apply the service to certaintraffic propagating in the network. The service device can be locatedoutside of the network that contains a network element that generatedthe PMU data. In addition, the service device can be provisioned at alast-hop router in relation to at least one member of the group ofsubscribers identified by the multicast group address. In certaininstances, the service is a phasor data concentration service.

Example Embodiments

Turning to FIG. 1A, FIG. 1A is a simplified block diagram illustrating aportion of grid system 10 in accordance with one embodiment of thepresent disclosure. Grid system 10 may not necessarily be a singleentity, but reflective of an aggregate of multiple networks and multiplepower generation companies cooperating in order to deliver energy totheir subscribers. In general terms, grid system 10 can offer ageneral-purpose approach to managing PMU data in the network. In morespecific implementations, grid system 10 is configured to convert apoint-to-point arrangement to a network-based publish-and-subscribeparadigm in order to increase network performance. In one particularexample implementation, this conversion can be executed via a multicastprotocol, which can effectively manage data flows from a certain numberof PMUs (e.g., ‘M’ PMUs) to a corresponding number of endpoints (e.g.,‘N’ endpoints). In addition, grid system 10 can be configured tovirtualize services in the network such that PDC stacking is avoided.PDC stacking refers to the notion of multiple PDC devices systematicallyreceiving redundant data streams, which unnecessarily creates overheadand which degrades network performance.

In operation, packet propagation within grid system 10 can involvemultiple destinations and, similarly, be sourced through multipleorigins. In a general sense, an arbitrary mix/match of network sourcesand network destinations can be achieved within the framework of gridsystem 10. Furthermore, it should be noted that such activities canoccur without placing an additional burden on the PMUs to participate inthe data flow management operations. Moreover, these activities canoccur without requiring external servers to be involved because thenetwork infrastructure (e.g., a first-hop router) is incurring therequisite processing work. This can be significant because PMUs commonlylack processing capabilities. Moreover, most legacy PMUs are unable tobe suitably upgraded or enhanced to offer higher-level processingcapabilities. In essence, grid system 10 can offload intensiveprocessing to network devices capable of handling such processingresponsibilities. From the perspective of the PMU, it can continue tooperate as if it is functioning in a more simplistic point-to-pointarchitecture, even though multicasting is being performed in grid system10. Stated in different terms, the PMU is unaware of the processing thatoccurs at the first hop-router in certain implementations describedherein. Hence, legacy PMU infrastructure does not have to be overhauledin order to achieve the teachings of the present disclosure. Instead, amore capable first-hop router can be configured to perform importantmulticasting activities, which allow for a preservation of an existingPMU architecture.

From an operator perspective, one or more administrators of grid system10 can manage varying levels of communication and coordination for thearchitecture. In an embodiment, grid system 10 is a smart grid, whichcan be viewed as a type of electrical grid that can be configured topredict (and intelligently respond to) the behavior and actions ofelectric power users and providers connected to the grid. This wouldallow grid system 10 to efficiently deliver reliable, economic, andsustainable electricity services. Grid system 10 may include substations12, a control center 14, and a first network 66, which can be a privatelow-latency wide area (WAN) in particular implementations of the presentdisclosure.

Each of substations 12 can include a respective PMU 26, a phasor dataconcentrator (PDC) 28, a substation network 84, and a first-hop router(FHR) 32. A PMU can be representative of any type of network elementthat can measure the electrical waves on an electricity grid (e.g.,using a common time source for synchronization). The timesynchronization aspect allows synchronized real-time measurements ofmultiple remote measurement points on grid system 10. In certaincontexts, these PMUs can include synchrophasors that represent measuringdevices for various power systems. A PMU can be a dedicated device, asensor, a software module, a proprietary device, a protective relay, orany other suitable combination of hardware, software, or components tobe used in conjunction measuring any form of energy within grid system10. Along similar lines, the term ‘PMU data’ is meant to encompass anytype of information generated by such PMU devices.

Substations 12 are configured to transform voltage from high to low, lowto high, and/or measure the operating status and overall health of gridsystem 10. Substations 12 are also configured to communicate withcontrol center 14 across first network 66. Control center 14 may includea last-hop router (LHR) 64, a control center network 98, and a PMU dataconsumers 70 segment in particular configurations of grid system 10.

Turning to FIG. 1B, FIG. 1B is a simplified block diagram illustrating aportion of grid system 10. Grid system 10 may further include a secondnetwork 68 (e.g., a North American Synchrophasor Initiative (NASPI)WAN), a second control center 20 (e.g., a North American ElectricReliability Corporation (NERC) control center), a third control center22 (e.g., a Regional Transmission Organizations (RTO) control center),and a utility bar substation 24. Second network 68 can be incommunication with first network 66 (e.g., through a set of routers 38).First network 66 and second network 68 are configured to allow for thedeployment and use of networked phasor measurement devices (e.g., PMUs26), PMU data-sharing, applications development and use, research andanalysis for real-time operations, power system planning, and forensicanalysis of grid disturbances.

Second control center 20 may include LHRs 64, control center network 98(e.g., a NERC control center network), and PMU data consumers 70. Secondcontrol center 20 may be used by the NERC to establish and enforcereliability standards including developing standards for power systemoperation, monitoring and enforcing compliance with those standards, andassessing resource adequacy. The NERC may also use second control center20 to investigate and analyze the causes of significant power systemdisturbances in order to help prevent future events that inhibit theability of grid system 10 to effectively deliver power to itsconstituents.

Third control center 22 may include LHRs 64, control center network 98(e.g., a RTO control center network), and PMU data consumers 70. Thirdcontrol center 22 may be configured to allow an RTO to move electricityover large interstate areas and coordinate, control, and monitor anelectricity transmission grid, which is larger and which has much highervoltages than a typical power company's distribution grid. Utility barsubstation 24 may include FHRs 32, substation networks 84, and PMUs 26.PMUs 26 and substation networks 84 may be in communication with FHRsthrough a utility bar WAN. Utility bar substation 24 may be a substationof an electrical provider other than the electrical provider ofsubstation 12.

Turning to FIG. 1C-1, FIG. 1C-1 is a simplified block diagramillustrating a portion of control center 14 within grid system 10.Control center 14 may include PMU data consumers 70, network switches62, and a storage 42. Storage 42 may include a processor 88 a and amemory 90 b. Storage 42 may be used by one or more PMU data consumers 70to store PMU data and the results of services performed on the PMU data.PMU data consumers 70 may perform a variety of services on PMU dataincluding geospatial analysis, phasor analysis and historian (timeseries database), analytics applications, visualization applications,complex event processing (CEP), management of PMUs 26, request tracker(RT) integration, etc. FIG. 1C-2 is a simplified block diagramillustrating a portion of control center 14 in grid system 10. Controlcenter 14 may include network switches 62 and LHR 64. Network switches62 may include core switches and service switches. Service switches areconfigured to route data to an aggregation layer configured to act as aservices layer, and to perform services such as loadbalancing, securesocket layer (SSL) optimization, firewalling, etc.

In one particular instance, grid system 10, first network 66, secondnetwork 68, substation network 84, and control center network 98 can beapplicable to communication environments such as an enterprise wide areanetwork (WAN) deployment, cable scenarios, broadband generally, fixedwireless instances, fiber to the x (FTTx), which is a generic term forany broadband network architecture that uses optical fiber in last-milearchitectures. Grid system 10, first network 66, second network 68,substation network 84, and control center network 98 may include aconfiguration capable of transmission control protocol/internet protocol(TCP/IP) communications for the transmission and/or reception of packetsin a network. In addition, grid system 10, first network 66, secondnetwork 68, substation network 84, and control center network 98 mayalso operate in conjunction with a user datagram protocol/IP (UDP/IP) orany other suitable protocol, where appropriate and based on particularneeds.

In operation, grid system 10 is configured to provide an improvedelectrical grid architecture offering an enhanced PMU design andimplementation, along with improved PMU applications. In regards to thefirst area, the implementation of PMUs within grid system 10 can addressthe issues of standards, communication, data management, testing,calibration, and PMU placement. Note that certain synchrophasorguidelines for the power system can define a synchrophasor measurement,as well as providing a method of quantifying the measurements, qualitytest specifications, and data transmission formatting for real-time datareporting. Separately, in response of the high scan rate intrinsic toPMUs, grid system 10 offers an architecture to meet the requirement forwide area monitoring, protection, and control scheme. Moreover, new dataand information management architecture and technology are also providedby grid system 10 to enable and to enhance the applications of PMUs inwide area protection and control. PMUs are involved in extensiveapplications such that grid system 10 can offer a provisioning strategyfor PMUs to reduce the economic burden for the utilities and, further,maximize the performance using a limited number of PMUs.

A second aspect of grid system 10 involves several PMU applications forpower system protection and control. As detailed below, grid system 10offers features including improvements on state estimation, oscillationdetection and control, voltage stability monitoring and control, loadmodeling validation, system restoration, and event analysis. Theseactivities are detailed below with reference to corresponding FIGURES.

In operation, grid system 10 can properly account for safeguards such aspower system protection and control. The installation of synchronizedPMUs in grid system 10 can improve both of these safeguards.Synchronized phasor measurements (i.e., PMU data) can be used to monitorand control the dynamic performance of a power system: particularlyduring high-stress operating conditions. A wide area measurement system(WAMS) that gathers real-time phasor measurements by PMUs (across abroad geographical area) has been gradually implemented in the gridarchitecture.

In practice, state estimation can play a significant role in thereal-time monitoring and control of power systems for grid system 10.For example, state estimation can process redundant measurements and,further, provide a steady-state operating environment for advancedenergy management system (EMS) application programs (e.g., securityanalysis, economic dispatch, etc.). After receiving field measurementdata, network parameter, network topology, and other information, thestate estimation can filter incorrect data to ensure that the estimatedstate is correct. Through state estimation, a system operator has theability to observe the operating conditions of grid system 10.Furthermore, the consistent data provided by the state estimationprovides a starting point for studying the effects due to the loss oftransmission lines, or of generation units.

Typical state estimation generally uses measured voltage, current, realpower, and reactive power to determine the operating condition of theelectric network. Certain limitations persist in the traditional stateestimation, and many of these limitations stem from the fact that it istechnically more difficult and computationally more expensive toestimate the most likely state of the system based on measured voltage,current, real power, and reactive power. Further, traditional stateestimation is typically solved at intervals of minutes, which means thatthe results provided by state estimation may be stale.

In certain implementations of grid system 10, PMUs 26 can be configuredto provide globally time-synchronized phasor measurements with a certainaccuracy (e.g., one microsecond for bus voltages and line currents).Additionally, PMUs 26 may improve state estimation by minimizingdeficient data processing, improving state estimation accuracy, allowingfor dynamic state estimation, and facilitating an acceptable researchrequirement in state estimation.

Note that because of the competition between utilities and thederegulation of the electric power markets, it is common to transferlarge amount of electrical power from distant generators to load throughlong transmission lines. The voluminous amount of electric powertransmitted through the existing networks might result in transmissionbottlenecks and oscillations of power transmission systems. The systemoscillation originates from the interconnected generators in the system.The interconnected synchronized generators typically have the ability toremain synchronized because of the self-regulating properties of theirinterconnections. However, if one generator deviates from thesynchronous speed, the rest of the generators in the system will providepower in order to reduce the speed deviation. Due to the effect ofinertia on the generators, the whole system (or part of the system)becomes imbalanced (i.e., starts to swing). Normally, if the initialdisturbance is not significant (such as a small change in load), theoscillations will decay and the system will maintain stability. If theinitial disturbance is significant (such as a few mega-watts (MWs) loadlost), the oscillations may cause the system to loose synchronism, wherethe system becomes vulnerable to a potential collapse.

In order to keep the system stable, system oscillation can be controlledeither by operators or by automatic control through adjusting the outputof generators. However, if a new system operating condition occurs thatcauses the oscillatory to lightly dampen, the operators may overlookthis new condition and, thus, jeopardize system operations. Advancedmonitoring of the power system can help the system operators to assesspower system states accurately, control the system appropriately, andavoid a total blackout. The synchronized PMUs 26, which can provide themeasurements with both magnitudes and angles, and which are timesynchronized with an accuracy of one microsecond, offer an opportunityfor power system oscillation detection and control. Fed with the voltageand current phasors (i.e., PMU data), a PMU-based power oscillationmonitoring function manages the input phasors and, further, detectsdifferent power swing (oscillation) modes. The PMU-based poweroscillation monitoring function has the ability to quickly identify theamplitude, frequency and the damping of swing rate, which may engenderangular instability.

It is worth noting that voltage stability is closely related to theloadability of a transmission network. In power systems, this may occuras a precursor to the traditional frequency instability problem. Aspower systems are pushed to transfer more and more power, environmentalconstraints restrict the expansion of the transmission network. When theneed for long-distance power transfer is increased, voltage stabilityproblem becomes a significant concern in planning and operatingelectrical power systems. To assist in the planning and operation ofelectrical power systems, new measurement devices and high-speedcommunication systems have become available in transmission systemoperation. Based on these technologies, measurement-based on-linevoltage stability monitoring and control becomes feasible, and thisability can raise the transfer limits and increase the security ofsystem operations. The use of synchronized PMUs 26 improves voltagestability monitoring and control function through voltage instabilityload shedding (VILS). This includes a focus on local protection control,along with a wide area voltage stability monitoring and control function(having a focus on system wide voltage stability and control).

In operation, grid system 10 is configured to implement PMU technologyin order to effectively manage electricity. PMU 26 can provide thesynchronized phasor information of voltage and current with anappropriate accuracy. The time of restoring the power system to itsnormal operating state after a fault can be improved by providingmaintenance staff with more exact information about the location and thereason for the fault. Research has indicated that, for PMU-based faultlocation systems, the accuracy of pinpointing a fault increases from±2-±3% for a system without PMUs 26 to as accurate as ±0.6% in mostinstances for a system with PMUs 26.

Note that during any major grid disturbance, the restoration and eventanalysis of grid system 10 represents important issues to be resolved bythe system operator. For example, during a disturbance, system operatorsseek to restore the system as quick as possible in order to limit theimpact of the disturbance, and to conduct a complete event analysis todetermine the root cause (allowing lessons to be learned if a similarevent occurred). However, because of the computational burden andabsence of synchronized data, the process of system restoration andevent analysis is time consuming and technically difficult to implement.The use of synchronized PMUs 26 can address both system restoration andevent analysis for the system operator.

For example, once a disturbance happens in a power system, theprotection system should identify it correctly and take appropriateaction immediately in order to isolate and minimize the disturbancearea. After the area is isolated, the location and source of thedisturbance should be identified and repaired to restore the powerservice as quick as possible. The fault location problem has beenstudied extensively. For overhead transmission lines, it is timeconsuming to identify the fault location manually. However, the processcan be expedited using the recording data from several pieces ofequipment such as protective relay, digital fault recorder, etc., whichare located in substations and control centers. One method identified asimpedance-based fault location, which has been used in power industryfor a long time, uses the fault impedance to calculate the faultlocation. The fault impedance can be calculated by post-fault voltagesand currents. For example, the fault location may be determined usingthe known transmission line impedance (per-mile).

There are two main approaches in the impedance-based fault locationmethod: single ended and double ended. In the single-ended approach, thedata is sampled at one point in the transmission line. Therefore, thisapproach could be affected by several factors such as line switching,load condition, fault current, and fault resistance. In the double-endedapproach, the data is sampled at two ends of the transmission line. Theresult of this approach could be affected by factors such as groundresistance and communication failure. Both approaches are used in thepower industry, and both have the ability to reduce the amount of timerequired by maintenance crews to find the fault location and reason forthe fault. However, each one is time consuming and often inaccurate.

These issues can be addressed by measuring the magnitude and phaseangles of currents and voltages, where a single PMU of grid system 10can provide real-time information about power system events in the areaof PMU 26. PMU 26 can operate as a digital recorder with a synchronizedcapability that can be offered as a stand-alone physical unit, or afunctional unit within another protective device. In addition, multiplePMUs 26 can enable coordinated system-wide measurements. PMUs 26 canalso timestamp, record, and store the phasor measurements of powersystem events. Control centers can then perform services on the PMU dataand, further, can use the results to determine the health of grid system10.

PMU data can operate as viable status messengers (e.g., the “ears andeyes”) for grid system 10. The information streamed from PMU 26 can beused for post-mortem analysis, or for real-time diagnosis and control ofgrid system 10. A post-mortem analysis of events does not typicallyrequire low and bounded latency of information delivery across anetwork. However, the applications that require real-time control canbenefit if the end-to-end network latency is kept to a minimum and keptunder strict bounds (e.g., network latency jitter is kept controlled).

For example, if “R” is the PMU reporting rate, “N” is the network delayor latency in seconds, “J” is the network latency jitter in seconds, and“P” is the phasor data concentrator (PDC) processing delay in seconds,then 1/R>=(N+J+P) could be representative of the constrain. The formulaestablishes that the phasor measurement-reporting rate is indirectlyproportional to the reduction of the delay added by the network and theprocessing delay added by the PMU data (i.e., phasor data) processingnodes. To improve the visibility in the electrical grid and to viewtransient phenomenon, the sampling rate of sixty (60) to one hundred andtwenty (120) samples/second is considered the lower bound of anacceptable sampling rate. One hundred and twenty (120) samples/secondmay allow for an end-to-end network and for a processing delay ofapproximately 8.3 milliseconds.

While sixty (60) samples/second would allow for an end-to-end networkand would provide a processing delay of 16.7 milliseconds, in particularimplementations of grid system 10, the sampling rate may be as high asseventy-two thousand (7,200) samples/second. Seventy two thousand(7,200) samples/second would allow for an end-to-end network and providea processing delay of 138.9 microseconds. Additionally, network latencyis made up of message transmit serialization delay, message propagationdelay in a medium, message receive serialization delay, messageswitching (or forwarding) delay, message queuing delay message outputdelay (i.e., represents any message of equal or lower priority, which isserialized out of the link), etc. Propagation of light across twohundred (200) kilometers (kms) of fiber can take approximately one (1)millisecond (the speed varies depending on the material used toconstruct the fiber, etc.). The message switching time (e.g., in anapplication specific integrated circuit (ASIC)-based system) can liebetween five hundred (500) nanoseconds to about fifty (50) microseconds.

In operation, grid system 10 is configured to provide for an end-to-endlow latency and low jitter path. This is achieved by using an end-to-endhardware accelerated path. In certain implementations, ASIC forwardingengines can be employed to foster predictable latency (e.g., two (2) orthree (3) hops, as compared to variable hops (typically over three (3)).In a particular embodiment, a circuit-like explicit static path setupexists for an improved control of the network data. Multiple technologychoices exist for routing traffic including multiprotocol labelswitching traffic engineering (MPLS-TE) and MPLS transport profile(MPLS-TP). Grid system 10 can also offer a predictable failover, alongwith appropriate network convergence. This can include MPLS-TE basedfast reroute, MPLS-TP based path protection, network redundancy, andpredictable failover after one failure. Grid system 10 may include anMPLS-based core WAN network in certain example implementations of thepresent disclosure. The converged network may be able to carry both IPand non-IP traffic (e.g., IEC 61850 GOOSE, etc.) even over a WAN.

Grid system 10 can additionally offer a scalable network that minimizespacket replication, replicates packets at designated points, andintegrates cryptography without burdening packet replication at the endhost. Grid system 10 may also offer fault resiliency, and predictablequality of service (QoS) guarantees. As a result, the last node is notcompromised, where limited fault domains are provided. In addition, leafnode failure does not affect the entire grid architecture. For example,switch or link failure impacts traffic going through grid system 10,where the addition of a new leaf switch is hitless (i.e., does not bringdown the network). In addition, the elimination of PDC stacking may alsobe realized. Further, PMU traffic can be multicasted (which offers lowerand more predictable latency).

Grid system 10 may employ multicasting technologies for a number ofreasons. For example, one source may have multiple interested receiversseeking the same data such that multicasting would readily address thisissue. In addition, multicasting can achieve an efficient bandwidthutilization, while the traffic can be IP/UDP encapsulated. Moreover,multicasting offers an efficient PMU computation and communicationresource utilization to be enabled. Multicasting also allows membershiplists to be suitably managed. The PMU may not need to be burdened withmanaging the receivers, which are authorized to receive or view thetraffic on grid system 10.

Note that without such multicasting activities, PMUs would be relegatedto point-to-point communications and be involved in PDC stacking, whichsignificantly degrades network performance. Aside from multicasting,other publish and subscribe services and protocols can readily be usedin the context of the present disclosure. For example, such services andprotocols can include the use of enterprise server buses, messagebrokers, etc., although this may create additional overhead and may beless efficient.

Separately, security issues for PMU data traffic may involve lowpredictable latency security features in the architecture. For example,both in terms of security and information visibility, the architectureof grid system 10 can provide appropriate protocols for managing data,content jamming protection, port security, and IPv4/IPv6 sourceguarding, etc. Wire speed cyber security may be achieved with no latencypenalty, where strict RPF can be enforced at L3 boundaries. In oneembodiment, multicast access control lists (ACLs) can form a second lineof defense for PMU traffic leaving a secure network. ACLs on the networkdeny PMU traffic except for an S/G that has been permitted by a PMUmanager. ACLs can be enforced in grid system 10 with little increasedlatency.

There are two proposed directions for PMU data transfer. These include amiddleware-based solution, chaining approaches, PDC stacking, etc. Theseapproaches can suffer from various drawbacks such as a lack of adequatescalability in the solution, few operational field deployments, and theintroduction of detrimental performance affects, which may includeadding significant PMU message propagation delay. In addition,non-standard implementations may vary from any standardization acrossvendors.

PMUs 26 typically conduct measurements of a target subject and packagethe PMU data (i.e., results of the measurements) into one of variousformats such as GOOSE, SV, C37.118-2005, and IEC 61850-90-5. The use ofIP within various protocol documents related to GOOSE and SV messagesare typically encapsulated directly into Ethernet frames without IP,which constricts the scope for the transfer of data geographically.Adequate transport of GOOSE and SV messages across the WAN can requireuse of an end-to-end transport protocol. Separately, both C37.118-2005and IEC 61850-90-5 specify the use of the IP protocol transport (eitherIP multicast or unicast).

PMU measurement messages transmitted (using IP) can be transmitted usingIP unicast to predefined receivers that are typically PDCs 28 orSuper-PDCs (i.e., integrated PDC functionality and service applicationswithin a single unit). The IP transport layer protocol widely used isUDP. However, some implementations utilize TCP for PMUcontrol/configuration and/or data transfer. GOOSE and SV messagestypically remain within the confines of the LAN nearby, where theyoriginate or where they are transferred by collector serviceapplications using a backhaul process interconnect after being locallyconsumed. Implementations utilizing Ethernet virtual LAN (VLAN) framedmessages are also employed, but still suffer from various limitationswhen implemented in WAN environments.

PDCs 28 can receive PMU data and concentrate (or combine) the PMU datainto a unified output stream. PDCs 28 can also time-synchronize themessages for temporal relevance by correlating their timestamps(originally instantiated at PMU 26) against each other. PDC 28 can thenoutput this combined message stream to another PDC 28 (referred to asPDC stacking, when PMU messages traverse multiple daisy-chained PDCs 28on their journey to an operations center or control center 14).Eventually the PMU messages arrive at an operations center. Along thepath from PMU 26 to the operations center, various actions (e.g., localprotection, tele-protection, etc.) can be performed at intermediatepoints (e.g., substations 12 that might be along the network path) basedon an evaluation of the PMU measurements and their comparison to PMUmeasurements from other parts of the utility grid or from other utilitygrids. In addition, PMU measurement data may also travel external to thelocal utility, for example, to a regional entity such as an ISO/RSO.

The dependence on PDC forwarding (or in the case of an alternateproposed middleware solution, a middleware entity that forwards the PMUdata) introduces a number of negative effects that can have an impact ondelay, jitter, scalability of the system, availability of the system,etc. By removing PDCs 28 and other non-networking entities from thenetwork path between PMU 26 and any PMU data consuming entity (be theyPDCs 28, PMU data consumers 70, middleware components, etc.), a positiveimpact on how the network performs may be achieved. Additionally, thisconfiguration reduces the complexity of management of the network and,as the PMU network grows, scaling becomes less complex.

Implementation of an IP multicast architecture for PMU networking canhave a positive impact on the functions of grid system 10. Using amulticast architecture reduces the complexity of management of thenetwork and allows grid system 10 to scale with PMU 26 deployment andapplication complexity. IP multicast can have benefits such as a vastscalability in terms of resource efficiency (e.g., bandwidth), as wellas a large number of receivers that can be supported (essentiallyinfinite). IP multicast also offers a viable, tested technology basethat supports intra-domain and inter-domain architectures, where servicecomponent adaptation is not complex. However, most PMUs 26 transmit datausing IP unicast. To alleviate this issue, conversion from unicast tomulticast (external to PMU 26 itself) can be implemented to accommodatelegacy PMUs that cannot transmit using IP multicast. As such, a givenPMU 26 has been activated for message transmission, PMU 26 will output acontinuous stream of packets (typically one or more usually up to amaximum of four destinations) toward a preconfigured destination.

In one example implementation, the PMU messages are transmitted to FHR32 or to a gateway on a local network to which PMU 26 is logicallyconnected. FHR 32 can be the first node in a multicast tree from thesource (PMU 26) to the destination (i.e., a device such as PDC 28, PMUdata consumer 70, or another application service component located at anintermediate point in the network, at an operations center, a controlcenter, or in another network domain). Once PMU 26 has been instructedto begin transmitting, it will transmit to FHR 32 regardless of whetherthere are receivers present. If there are no receivers present, FHR 32will drop or discard the PMU packets until the receivers come on-line.

In essence, PMU 26 can be transmitting to hosts (referred to asapplication service components) that are located in a network, otherthan the local network (i.e., rather than being located inside the localnetwork and part of the forwarding path). These hosts are notnecessarily participating in the forwarding of the messages from thePMU. Such hosts are referred to as called receivers in IP multicastterminology. The receivers may be PMU data centers 70, or any otherappropriate network node.

In order for PMU messages to be forwarded from FHR 32 to theirappropriate destination, one or more destinations, or receivers shouldbe active within the multicast implementation. In order to becomeactive, a receiver should signal to the network that it wishes toreceive traffic from a specific multicast source. This source is usuallyspecified using an (S,G) pair. “S” represents the IP unicast address ofthe source (i.e., PMU 26) and “G” represents the group address thatassociates the set of receivers that will receive traffic from thespecific source. The group address is also referred to as a multicastaddress (also known as a Class E address). The group address is used ina multicast routing table to identify the downstream (i.e., towards thereceivers) egress ports on a router to which the specific multicasttraffic can be transmitted in order to reach one or more receivers forspecific traffic. FHR 32 can transmit each IP packet, which contains aPMU message, using the group address “G” in the IP destination addressfield and the source address “S” in the IP source address field.

A receiver (such as PDC 28, PMU data consumer 70, or other applicationservice component) that seeks to receive traffic from a specific sourcePMU 26 (e.g., source Sa) may utilize the Internet Group ManagementProtocol (IGMP) Version 3, which supports protocol independent multicastsource specific multicast (PIM-SSM). The receiver may signal to thelocal gateway router (where the gateway is also acting as LHR 64 in thisinstance) that it wishes to receive traffic from the specific source,Sa. The receiver should also specify that it belongs to a group address,Ga.

To enable coordinated system-wide measurements from multiple PMUs 26,the data (e.g., synchrophasor measurements) from each PMU 26 may have atime tag or stamp (e.g., a universal time coordinated (UTC) time tag orstamp). In one example, the time tag consists of three numbers: asecond-of-century (SOC) count, a fraction-of-second count, and a timestatus value. The SOC count is a four (4)-byte binary count in secondsfrom midnight (00:00) of Jan. 1, 1970, to the current second. Leapseconds can be added to (or deleted from) this count to keep itsynchronized with the UTC time. Insertion of a leap second can result intwo successive seconds having the same SOC count, which aredifferentiated by the leap second bit in a FRACSEC word. Using thisconvention, time count can be determined from the current time bymultiplying the number of days since Jan. 1, 1970 (1/1/70) by the numberof seconds per day, eighty-six thousand and four hundred (86,400). TheSOC timestamp is the same as is used by the UNIX computer system, andsimilar to those used by other computer systems including DOS, MAC OS,and networks [i.e., network time protocol (NTP)].

The seconds can be divided into an integer number of subdivisions by aTIME_BASE integer. A fraction of a second count can be an integerrepresenting the numerator of the fraction of a second with theTIME_BASE serving as the denominator. Compatibility with IEC 61850:2000can include a TIME_BASE value of two raised to the power of twenty-four(2̂24). The fraction of a second count can be zero (0) when it coincideswith a one (1) second rollover. The time tag may be applied to each ofthe communication frames.

Synchrophasor measurements can be synchronized to UTC time with accuracysufficient to meet the accuracy requirements. Note that a time error ofone (1) second corresponds to a phase error of 0.022° for a sixty (60)Hertz (Hz) system and 0.018° for a fifty (50) Hz system. A phase errorof 0.01 radian or 0.57° will by itself cause a 1% total vector error(TVE). This corresponds to a maximum time error of plus-or-minustwenty-six (±26) seconds for a sixty (60) Hz system, and plus-or-minusthirty-one (±31) seconds for a fifty (50) Hz system. The system shouldbe capable of receiving time from a highly reliable source, such as aGlobal Positioning System (GPS) element, which can provide sufficienttime accuracy to keep the total vector error (TVE) within the requiredlimits and, further, provide an indication of loss of synchronization. Aflag in the data output can be provided to indicate that a loss of timesynchronization can be asserted when a loss of synchronization wouldcause the TVE to exceed the limit, or within one (1) minute of an actualloss of synchronization, whichever is less. The flag can remain setuntil data acquisition is resynchronized to the designated accuracylevel.

Turning to FIG. 2A, FIG. 2A is a simplified block diagram illustratingone possible set of details associated with the present disclosure. FIG.2A includes PMU 26, FHR 32, routers 38, LHRs 64, first network 66,second network 68, and PMU data consumers 70 (i.e., subscriber). FHR 32may include unicast to multicast module 86. Unicast to multicast module86 may include a processor 88 b, and a memory 90 b. PMU data consumers70 can include a processor 88 c and a memory 90 c in a particularimplementation of the present disclosure.

In operation, unicast to multicast module 86 is configured to convert aunicast transmission of PMU data in to a multicast transmission. Forexample, PMU 26 can send PMU data in a unicast transmission 72 to FHR32. FHR 32 is the first node in a multicast tree and FHR 32 converts theunicast transmission 72 of the PMU data to a multicast transmission 74of the PMU data. Multicast transmission 74 can be subsequentlycommunicated to PMU data consumers 70.

Multicast transmission 74 of the PMU data traverses first network 66and/or second network 68 to LHR 64. LHR 64 is the gateway from firstnetwork 66 or second network 68 to PMU data consumer 70. By convertingthe unicast PMU data transmission to a multicast transmission, PDCstacking or chaining can be avoided. The multicast transmission from FHR32 can allow for adequate scalability, alleviate the introduction ofdetrimental performance affects (e.g., adding to PMU message propagationdelay), and allow for non-standard implementations that may vary fromany standardization across vendors. In addition, each PMU 26 does nothave to replicate traffic, nor manage membership lists of subscribers orPMU data consumers, which are interested in the PMU data.

Turning to FIG. 2B, FIG. 2B is a simplified block diagram illustratingone possible set of details associated with substation 12. Substation 12can include PMUs 26, PDC 28, switches 30 (i.e., aggregation switches andaccess switches), and FHRs 32. PMUs 26 may include a processor 88 e andmemory 90 e in a particular implementation of the present disclosure.PDC 28 may also include a processor 88 d and a memory 90 d. FHRs 32 mayinclude a unicast to multicast module 86, which may include a processor88 b and a memory 90 b in a particular example. PMUs 26 may bereflective of a dedicated device, or can be incorporated into aprotective relay or other device. In addition, PMUs 26 may be dispersedthroughout grid system 10 to form a phasor network, where they areconfigured to measure the electrical waves on grid system 10 using acommon time source for synchronization. The common time source may beprovided by a GPS clock 82, as is illustrated in FIG. 2B.

The placement of PMUs 26 can be determined based on two major factors:system characteristic and intended application. Regarding the systemcharacteristic, topology configuration (system size, node location, weaknodes and power flow pattern, etc.) and communication ability (availablechannels, bandwidth limit, time delay, etc.) can influence theprovisioning of PMUs 26. Topology configuration and communicationability are important to PMUs 26 placement because they can determinethe potential PMU sites and communication pattern, which can form thestrategy for PMUs 26 provisioning.

The application of out-of-step protection suggests that the placement ofPMUs 26 should be performed by factoring in the observability of thegenerator rotor angle in real-time. The situation becomes morecomplicated when multiple applications are required. As a result,different PMUs 26 placement schemes may be developed first, where thoseschemes are evaluated together and a final optimal scheme can beresolved using various methodologies. PDC 28 can form a node in asystem, where PMU data (i.e., phasor data) from a number of PMUs 26 (orPDCs 28) can be correlated (by time-tag) to create a measurement set.PDC 28 may provide additional functions as well such as performingvarious quality checks on the PMU data, insertion of appropriate flagsinto the correlated data stream, etc. PDC 28 may also monitor theoverall measurement of substation 12 and, further, provide a display anda record of performance.

In operation, PDC 28 can serve as the hub of the measurement system,where data from a number of PMUs 26 or other PDCs 28 is broughttogether, and then fed out to other applications. PDC 28 can also beconfigured to perform extensive functions in the measurement system,buffer the data stream internally, and spool the data to otherapplications. In addition, PDC 28 can send out a continuous stream of amore comprehensive data set over an Ethernet link, or it can send outselected data based on an application or a flag status. PDC 28 is alsoconfigured to monitor the overall network and, further, may include anetwork client program for user access. A specific program on PDC 28 canindicate system disturbances and subsequently record a file thatdocuments the disturbance.

Switches 30 can connect the network components of substations 12. GPSclock 82 can be included within switches 30 to provide a precise timingmechanism. This could allow for the synchrophasor measurement of voltageand current on grid system 10, as well as synchronization of data fromPMUs 26. Switches 30 can connect PMUs 14 and PDC 28 to first-hop routers32. First-hop routers 32 (or gateways) are reflective of the first nodein a multicast “tree” from the source (a PMU 26) to the destination(e.g., a device such as an application service component located at anintermediate point in grid system 10, PMU data consumer 70, controlcenter 14, a NERC control center, a RTO control center, utility barsubstation 24, etc.). First-hop routers 32 can receive data from PMUs 26and PDC 28 and then communicate the data across first network 66 to PMUdata consumers 70 (i.e., subscribers).

Note that because FIGS. 2C-1 and 2C-2 are related, their capabilitiesand functionalities are discussed together. FIGS. 2C-1 and 2C-2 aresimplified block diagrams illustrating one possible set of detailsassociated with a portion of grid system 10. More specifically, FIG.2C-1 may include substation 12, first network 66, and control center 14.In this particular example, substation 12 may include first PMU 26 a,second PMU 26 b, PDC 28, substation network 84, and FHR 32. Controlcenter 14 may include LHR 64, control center network 98, and PMU dataconsumers 70 in this particular configuration. In addition, FIG. 2C-2may include substation 12, control center 14, second network 68, secondcontrol center 20, third control center 22, and utility bar substation24. Second control center 20 may include LHR 64, control center network98 (e.g., a NERC control center network), and PMU data consumers 70.Third control center 22 may include LHR 64, control center network 98(e.g., a RTO control center network), and PMU data consumers 70. Utilitybar substation 24 may include FHR 32, substation network 84, and PMUs 26in a particular implementation of the present disclosure.

In operation, first PMU 26 a is configured to generate a first PMU datasignal 94 and second PMU 26 b is configured to generate a second PMUdata signal 96. PDC 28 and one or more PMU data consumers 70 may seek toreceive first PMU data signal 94 and/or second PMU data signal 96.However, PMU 26 a and PMU 26 b can typically unicast PMU data signals.

To transmit the PMU data to multiple PMU data consumers 70, PMU 26 a andPMU 26 b can unicast PMU data to FHR 32. FHR 32 may include unicast tomulticast module 86 (shown in FIG. 2A and 2B). A specific PMU dataconsumer 70 can communicate with FHR 32 and indicate that the specificPMU data consumer 70 seeks to receive the PMU data. For example, fourPMU data consumers 70 (two PMU data consumers 70 from control center 70,one in second control center 20, and one in third control center 22) mayrequest first PMU data signal 94 from first PMU 26 a and two PMU dataconsumers 70 (two PMU data consumers 70 from control center 70) mayrequest second PMU data signal 96 from second PMU 26 b. Second PMU datasignal 96 may contain only the voltage recorded by second PMU 26 b,while first PMU data signal 94 may contain additional data.

PMU data consumers that requested the PMU data can be added to amulticast group list in FHR 32 (e.g., the group list stored in memory 90b of unicast to multicast module 86). After receiving the unicasttransmission from PMU 26 a and PMU 26 b, FHR 32 is configured to convertthe unicast transmission to a multicast transmission. For example, firstPMU data signal 94 may start as a unicast transmission from first PMU 26a to FHR 32. At FHR 32, first PMU data signal 94 can be converted to amulticast transmission and subsequently communicated to the four PMUdata consumers 70, which requested first PMU data signal 94. Similarly,second PMU data signal 96 may start as a unicast transmission fromsecond PMU 26 b to FHR 32. At FHR 32, second PMU data signal 94 can beconverted to a multicast transmission and subsequently communicated tothe two PMU data consumers 70, which requested second PMU data signal98.

Turning to FIG. 2D, FIG. 2D is a simplified block diagram illustratingone possible set of details associated with a data frame 46 for use ingrid system 10. Data frame 46 may include a SYNC field 48, a FRAMESIZEfield 50, an ID CODE field 52, a SOC field 54, a FRACSEC field 56, adata section 58 (which may include data fields), and a CHK field 60.Data messages can reflect the measurements made by a given PMU. Onepossible organizational example of data frame 46 is illustrated below asTABLE 1.

TABLE 1 Data frame organization No. Field Size (bytes) Comment 1 SYNC 2Sync byte followed by frame type and version number. 2 FRAMESIZE 2Number of bytes in frame, defined in 6.2. 3 IDCODE 2 PMU/DC ID number,16-bit integer, defined in 6.2. 4 SOC 4 SOC time stamp, defined in 6.2,for all measurements in frame. 5 FRACSEC 4 Fraction of Second and TimeQuality, defined in 6.2, for all measurements in frame. 6 STAT 2Bitmapped flags. 7 PHASORS 4 × PHNMR Phasor estimates as defined inClause 5. May be single-phase or or 3-phase positive, negative, or zerosequence. Values are 4 or 8 bytes 8 × PHNMR each depending on the fixed16-bit or floating-point format used, as indicated by the configurationframe. 8 FREQ 2/4 Frequency (fixed or floating point). 9 DFREQ 2/4 Rateof change of frequency (fixed or floating point). 10  ANALOG 2 × ANNMRAnalog data, 2 or 4 bytes per value depending on fixed- or floating- orpoint format used, as indicated by the configuration frame. 4 × ANNMR11  DIGITAL 2 × DGNMR Digital data, usually representing 16 digitalstatus points (channels). Repeat 6-11 Fields 6-11 are repeated for asmany PMUs as in NUM_PMU field in configuration frame. 12+ CHK 2CRC-CCITT

In an embodiment, frames used in grid system 10 can include four messagetypes: data, configuration, header, and command. The first three messagetypes can be transmitted from the PMU/PDC, where the command messagetype is received by PMU 26/PDC 28 and is used in the control of PMU 26.Frames in grid system 10 may begin with a two (2)-byte SYNC word in SYNCfield 48. The SYNC word can provide synchronization and frameidentification and bits four (4)-six (6) in the SYNC word can designatethe frame type. FRAMESIZE field 50 may include a two (2)-byte FRAMESIZEword. ID CODE field 52 may include a two (2)-byte IDCODE and SOC field54 may include a timestamp consisting of a four (4)-byte SOC. FRACSECfield 56 may include a four (4)-byte fraction of second, which includesa twenty-four (24)-bit fraction-of-second integer and an eight (8)-bitTime Quality flag. IDCODE positively identifies the unit sending orreceiving the message.

The frames can terminate in the check word (CHK), for example,CRC-CCITT. CRC-CCITT can use the generating polynomial X16+X12+X5+1 withan initial value of negative one ((−1) (hex FFFF) and no final mask.Frames (e.g., data frame 46) in grid system 10 can be transmitted withno delimiters. The SYNC word can be transmitted first and the check word(i.e., CHK) last. Two (2) and four (4)-byte words can be transmittedmost significant byte first (network or “big endian” order). Exampleword definitions that may be common to types of frames propagating ingrid system 10 are provided below in TABLE 2.

TABLE 2 Word definitions common to all frame types Size Field (bytes)Comments SYNC 2 Frame synchronization word. Leading byte: AA hex Secondbyte: Frame type and Version, divided as follows: Bit 7: Reserved forfuture definition Bits 6-4: 000: Data Frame 001: Header Frame 010:Configuration Frame 1 011: Configuration Frame 2 100: Command Frame(received message) Bits 3-0: Version number, in binary (1-15), version 1for this initial publication. FRAMESIZE 2 Total number of bytes in theframe, including CHK. 16-bit unsigned number. Range = maximum 65535.IDCODE 2 PMU/DC ID number, 16-bit integer, assigned by user, 1 to 65 534(0 and 65 535 are reserved). Identifies device sending and receivingmessages. SOC 4 Time stamp, 32-bit unsigned number, SOC count startingat midnight 01-Jan-1970 (UNIX time base). Ranges 136 yr, rolls over 2106AD. Leap seconds are not included in count, so each year has the samenumber of seconds except leap years, which have an extra day (86 400 s).FRACSEC 4 Fraction of Second and Time Quality, time of measurement fordata frames or time of frame transmission for non-data frames. Bits31-24: Time Quality as defined in 6.2.2. Bits 23-00: Fraction-of-second,24-bit integer number. When divided by TIME_BASE yields the actualfractional second. FRACSEC used in all messages to and from a given PMUshall use the same TIME_BASE that is provided in the configurationmessage from that PMU. CHK 2 CRC-CCITT, 16-bit unsigned integer.

Data frame 46 may include measured data and be identified by having bitsfour (4)-six (6) in the SYNC field 47 set to zero (0). The configurationcan be a machine-readable message describing the configuration data thatcan be sent by/or to PMU 26/PDC 28 (where calibration factors may alsobe provided). Header information can be human-readable descriptiveinformation sent from PMU 26/PDC 28 and provided by the user. Commandscan be machine-readable codes sent to PMU 26/PDC 28 for control orconfiguration. Information may be stored in any convenient form in PMU26/PDC 28 itself, but when transmitted it can be formatted as frames. Incertain implementations, fields may be of a fixed-length, having nodelimiters.

One possible implementation associated with word definitions for dataframe 46 is illustrated in TABLE 3.

TABLE 3 Word definitions unique to data frames Size Field (bytes)Comments STAT 2 Bitmapped flags. Bit 15: Data valid, 0 when PMU data isvalid, 1 when invalid or PMU is in test mode. Bit 14: PMU errorincluding configuration error, 0 when no error. Bit 13: PMU sync, 0 whenin sync. Bit 12: Data sorting, 0 by time stamp, 1 by arrival. Bit 11:PMU trigger detected, 0 when no trigger. Bit 10: Configuration changed,set to 1 for 1 min when configuration changed. Bits 09-06: Reserved forsecurity, presently set to 0. Bits 05-04: Unlocked time: 00 = synclocked, best quality 01 = Unlocked for 10 s 10 = Unlocked for 100 s 11 =Unlocked over 1000 s Bits 03-00: Trigger reason: 1111-1000: Availablefor user definition 0111: Digital 0110: Reserved 0101: df/dt high 0100:Frequency high/low 0011: Phase-angle diff 0010: Magnitude high 0001:Magnitude low 0000: Manual PHASORS 4/8 16-bit integer values:Rectangular format: Real and imaginary, real value first 16-bit signedintegers, range −32 767 to +32 767 Polar format: Magnitude and angle,magnitude first Magnitude 16-bit unsigned integer range 0 to 65 535Angle 16-bit signed integer, in radians × 10⁴, range −31 416 to +31 41632-bit values in IEEE floating-point format: Rectangular format: Realand imaginary, in engineering units, real value first Polar format:Magnitude and angle, magnitude first and in engineering units Angle inradians, range −π to +π FREQ 2/4 Frequency deviation from nominal, inmillihertz (mHz) Range - nominal (50 Hz or 60 Hz) −32.767 to +32.767 Hz16-bit integer or 32-bit floating point. 16-bit integer: 16-bit signedintegers, range −32 767 to +32 767. 32-bit floating point: actualfrequency value in IEEE floating-point format. DFREQ 2/4 Rate-of-changeof frequency, in Hz per second times 100 Range −327.67 to +327.67 Hz persecond Can be 16-bit integer or IEEE floating point, same as FREQ above.ANALOG 2/4 Analog word. 16-bit integer. It could be sampled data such ascontrol signal or transducer value. Values and ranges defined by user.Can be 16-bit integer or IEEE floating point. DIGITAL 2 Digital statusword. It could be bitmapped status or flag. Values and ranges defined byuser.

Real-time data transmission can occur concurrently with the measurementprocess. If PMU 26 is to be used with other systems, where the PMU datainformation is to be transmitted in real-time, implementation of thisprotocol is used for conformity with a standard. If PMU 26 is used onlyfor PMU data archiving or recording, then such a protocol is notrequired. (Implementation of additional protocols for PMU datacommunication is not restricted to the one disclosed herein, as anycommunication system, mechanism, or media may be used for datatransmission.) Message frames can be transmitted in their entirety, asthey are specified. When used with a stacked protocol such as thefieldbus message specification (FMS) or the IP paradigm, the frame(including SYNC field 48 and CHK field 60) can be written into (and readfrom) the application layer interface. When used with more directsystems (such as raw Ethernet or RS-232), the frame can also be sentwith the CRC-CCITT, which assures data integrity. As a result, themessage protocol may be used for communication with a single PMU 26, orwith a secondary system that receives data from several PMUs 26. Thesecondary system may have its own user assigned ID code. The aboveprotocol allows for identifying information, such as the PMU IDCODE andstatus, to be imbedded in data frame 46 for proper interpretation of themeasured data.

Turning to FIG. 2E, FIG. 2E is a simplified block diagram illustratingone possible set of details associated with a portion of grid system 10.FIG. 2E may include a set of analog inputs 106, multiple anti-aliasingfilters 108, an analog-to-digital (A/D) converter 110, a phasormicroprocessor 112, a phase-locked oscillator 114, a GPS receiver 116,and a transmission module 118. In one example, analog input signals areobtained from the secondaries of voltage and current transformers andreceived at analog inputs 106. The analog input signals are filtered byanti-aliasing filter 108 to avoid aliasing errors. Subsequently, thesignals are sampled by A/D converter 110. A sampling clock can bephase-locked to the GPS time signal from GPS receiver 116. GPS receivers116 can provide uniform timestamps for PMUs 26 at different locations,where phasor microprocessor 112 is configured to calculate the values ofthe phasor. The calculated phasors (i.e., phasor values) and otherinformation can be transmitted to appropriate remote locations usingtransmission module 118. Transmission module 118 is configured tocommunicate data from PMU 26 using substation network 84.

In one example implementation, the synchrophasor representation X of asignal x(t) is the value given by Equation 1 below:

X=Xr+jXi=(Xm/√2)êjψ=Xm/√2(cos ψ+j sin ψ)   Equation 1

Xm/√2 is the rms value of the signal x(t) and ψ is its instantaneousphase angle relative to a cosine function at nominal system frequencysynchronized to universal time coordinated (UTC). The angle is definedto be 0° when the maximum of x(t) occurs at the UTC second rollover [one(1) pulse per second (PPS) time signal], and negative ninety (−90)° whenthe positive zero crossing occurs at the UTC second rollover.

Turning to FIG. 2F, FIG. 2F is a simplified flowchart 200 illustratingone potential operation associated with the present disclosure. At 202,data can be received from a PMU in a unicast transmission. For example,first-hop router 32 may receive PMU data in a unicast transmission fromPMU 26. At 204, the unicast transmission can be converted to a multicasttransmission. For example, unicast to multicast module 86 may convertthe unicast transmission into a multicast transmission in the network.At 206, the data is multicast to a subscriber of a multicast groupaddress. For example, first-hop router 32 may multicast the datareceived from PMU 26 to PMU consumers 70 in control center 14, a NERCcontrol center, a RTO control center, and/or utility bar substation 24.

Turning to FIG. 2G, FIG. 2G is a simplified flowchart 201 illustratingone potential operation associated with the present disclosure. At 208,data is received from a PMU in a unicast transmission. For example,first-hop router 32 may receive data in a unicast transmission from PMU26. At 210, the unicast transmission is converted to a multicasttransmission. For example, unicast to multicast module 86 may convertthe unicast transmission into a multicast transmission. At 212, thesystem determines if a new subscriber has been added to a multicastgroup that will receive the multicast transmission. For example, PMUdata consumer 70 in control center 14 may join a multicast group of PMUdata consumers 70 in a NERC control center, a RTO control center, and/orutility bar substation 24 to receive data from PMU 26.

If a new subscriber has not been added to the multicast group, then thePMU data is multicast to the multicast group, as illustrated in 214. Inan embodiment, subscribers to the multicast group are identified by amulticast group address. If a new subscriber has been added to themulticast group, then the system determines if a new multicast treeshould to be constructed, as illustrated in 216.

A multicast tree can be formed as a virtual minimum spanning tree (or aminimum connection of nodes), which connects members of the tree. Thenew multicast tree may need to be constructed to accommodate the newsubscriber. For example, the multicast group of PMU data consumers 70 ina NERC control center, a RTO control center, and/or utility barsubstation 24 may have a multicast tree that only goes through a NASPIWAN. To multicast data from PMU 26 to a PMU data consumer 70 in controlcenter 14, a new multicast tree that goes through the corresponding WANshould to be constructed. If a new multicast tree should be constructed,then a new multicast tree is constructed, as illustrated in 218, and thePMU data is multicast to the multicast group, as illustrated in 214. Ifa multicast tree does not need to be built, then the PMU data ismulticast to the multicast group, as illustrated in 214.

Turning to FIG. 2H, FIG. 2H is a simplified flowchart 203 illustratingone potential operation associated with the present disclosure. At 220,first PMU data is received from a first PMU in a first unicasttransmission. At 222, second PMU data is received from a second PMU in asecond unicast transmission. At 224, the first unicast transmission andthe second unicast transmission are combined into a multicasttransmission. At 226, the system is configured to determine if there ismore than one multicast group that will receive the multicasttransmission. If there is not more than one multicast group, then themulticast transmission (including the first PMU data and the second PMUdata) is communicated to the multicast group, as illustrated in 228.

If there is more than one multicast group, then the system is configuredto determine if each multicast group receives the same first PMU dataand the same second PMU data, as is illustrated in 230. If eachmulticast group receives the same first PMU data and the same second PMUdata, then the multicast transmission (including the first PMU data andthe second PMU data) is communicated to each multicast group, asillustrated in 232. If each multicast group does not receive the samefirst PMU data and the same second PMU data, then the first PMU data andthe second PMU data are formatted for each multicast group, asillustrated in 234. At 236, the appropriate first PMU data and theappropriate second PMU data are communicated to each respectivemulticast group.

Turning to FIG. 3A, FIG. 3A is a simplified block diagram illustratingone possible set of implementation details associated with substation12. Substation 12 may include PMU 26, PDC 28, switches 30, FHR 32, aservice device 76, a standby ISP router 78, and an active ISP router 80.Service device 76 may include a service module 92, a processor 88 f, anda memory 90 f. Service device 76 is configured to perform services onthe PMU data and subsequently multicast the results of the service tosubscribers. The services can be requested by PMU data consumer 70. Forexample, service device 76 is configured to perform service,replication, and masking activities. FHR 32 may include a unicast tomulticast module for converting a unicast transmission of PMU data to amulticast transmission. The unicast to multicast module may includeprocessor 88 b and memory 90 b. While service device 76 is shown insubstation 12, service device 76 may readily be provisioned in otherlocations of grid system 10.

PMU data sent from PMU 26 can be redirected (via SIA) to service device76. This can occur via a service insertion architecture (SIA) protocol,which can provide a platform-independent framework for servicevirtualization and dynamic service insertion into a network. Forexample, the devices at the edge of an SIA domain can classify theinterested traffic: placing the classification result inside of a sharedSIA context, and then redirecting the tagged packet to the next hopservice in the SIA service path. Each service hop in the path receivesthe packet, uses the shared context to identify the trafficclassification, and then applies the appropriate service policyassociated with the SIA classification. After service application, theedge devices can derive the next hop in the service path associated withthe shared context in the packet and then send the traffic to the nextservice node. The final service in the path removes the shared contextfrom the packet and forwards the packet to the original destination.

The replication and masking services can occur at service module 90without having to be inline, where the results of the service (i.e.,service data) can be sent to the proper destinations. If only a subsetof PMU traffic should be masked, then service module 90 can mask thesubset of traffic, where non-masked traffic is not processed by maskingservices in service module 90 but simply sent to FHR 32. Service device76 can be used to determine which packets require servicing. Servicedevice 76 in grid system 10 can leverage metadata to ensure that theproper order of service is applied. Service metadata can be used by thenetwork and by services to carry opaque information along the servicepath. The SIA control plane can ensure that services are functioningproperly and, further, may also provide alternatives if the failure ofservices occur.

In a particular embodiment, services do not need to be placed inlineand, therefore, do not affect network service level agreements (SLAs).Granularity can be applied for certain traffic in need of services,whereas other traffic does not. In addition, services can be addeddynamically by communicating with service device 76, which can performthe added service. When another service is required, no network orexisting service changes are required. Further, SIA pre/post servicepackets can be IP packets, where network forwarding remains relevant(e.g., TE, fast re-route, etc.).

SIA can provide an independent platform that offers a consistentarchitecture for adding high touch services to a network withoutrequiring topology changes. For example, first service nodes (SNs) andservice clients (SCLs) can register with a service directory/broker(SDB), which reflects any node/device within a network configured tostore and to provide a consistent domain-wide view of availableservices. For instance, an SN may register with the SDB that it is ableto provide firewall services for the network, while an SCL may registerwith the SDB that it desires firewall services. In response, the SDBreturns a service header to each of the SN and SCL that is specific tothe registered service.

According to another aspect of the architecture, certain traffic can beredirected with a prepended service header from SCLs to an appropriateSN in the network. This can occur independent of the physical locationsuch that the SN may perform the services as requested by the serviceheader (e.g., firewalling). In this manner, SCLs need not perform theservices desired/required by the traffic, but may instead redirect thetraffic to SNs within the network, which are specifically configured toprovide such services. The traffic may then be forwarded from the SNstoward its destination after the services have been performed.

SIA can provide a common framework (e.g., HA, registration, etc.) forservice abstraction. To the SIA framework, services look and feel thesame, thus freeing the services to focus on service details. SIA cancreate a network awareness (when appropriate) in services, and a serviceawareness in the network. Topology abstraction can enable servicedeployment without complex network engineering. SIA elements canparticipate in a control plane and the control plane can provide serviceinformation (e.g., up/down, load, etc.), high availability, loaddistribution, and security (e.g., authentication, encryption, etc.).Services can be registered with a service broker (e.g., network elementor PMU data consumer 70), and the service broker can determine whichservice device 76 can perform a requested service. The service brokermay be a standalone unit or part of PMU data consumer 70.

Turning to FIG. 3B, FIG. 3B is a simplified flowchart 300 illustratingone potential operation associated with the present disclosure. At 302,a service to be performed on PMU data is received. For example, amulticast group (or single PMU data consumer 70) can request thatreplication and masking be done on PMU data. At 304, a device to performthe service on the PMU data is identified. For example, service device76 that can perform the replication and masking is identified in gridsystem 10. In addition, a multicast tree (that incorporates themulticast group and service device 76) may be created such that servicedevice 76 is located near the multicast group, which requests theservice. At 306, a unicast transmission of the PMU data is received atthe device. In another embodiment, a multicast transmission of the PMUdata from an FHR is received at the device. At 308, the device performsthe service on the PMU data and then multicasts the results of theservice to a multicast subscriber group.

Turning to FIG. 3C, FIG. 3C is a simplified flowchart 301 illustratingone potential operation associated with the present disclosure. At 310,a service to be performed on PMU data is determined. At 312, asubscriber is identified for receiving the results of the service on thePMU data. For example, the subscriber may be PMU data consumer 70. At314, the system is configured to determine if the subscriber is part ofa multicast group, which will receive the results of the service. If thesubscriber is not part of a multicast group that will receive theresults of the service, then a device to perform the service isidentified near the subscriber, which will receive the results of theservice on the PMU data, as illustrated in 316. For example, servicedevice 76 that will perform the service may be located near LHR 64 andPMU data consumer 70, which requested the service. At 318, the PMU datais received at the device, and the results of the service on the PMUdata is communicated to the subscriber.

If the subscriber is part of a multicast group that will receive theresults of the service, then a device to perform the service isidentified near that multicast group, as illustrated in 320. Forexample, a multicast tree that incorporates the multicast group andservice device 76 may be created such that service device 76 is locatednear the multicast group that requests the service. At 322, the PMU datais received at the device, and the results of the service on the PMUdata can be multicast to the multicast group.

Turning to FIG. 4, FIG. 4 is a simplified block diagram illustrating onepotential operation associated with the present disclosure. FIG. 4 mayinclude a PMU manager 104, PDC 28, control center network 98, networkswitches 62, a firewall module 100, first network 66, FHR 32, and a PMUrelay 102. PMU data traffic can be communicated from PMU relay 102 toFHR 32. From FHR, the PMU data traffic can be communicated in amulticast transmission. Network switches 62 can be used to relay the PMUdata traffic to the correct destination. A centralized remedial actionscheme (CRAS) operation network intrusion prevention system (IPS) canoperate in a promiscuous mode, where traversal of firewall module 100 isrecommended for accessing any CRAS relay or server from a non-CRASdevice. For example, because PMU manager 104 and PDC 28 are not on thesame local network as PMU relay 102, firewall module 100 should betraversed before access to PMU relay 102 is allowed. In a particularembodiment, segmentation and path isolation for CRAS traffic may beprovided.

In one example, crypto protection for traffic can allow an owner of PMU26 to control PMU data that leaves a network (e.g., the network that mayinclude PMU 26) by using ACLs. For example, a group crypto may be usedfor protecting PMU traffic. Using a group key to encrypt the PMU trafficallows the PMU traffic to be multicast efficiently and securely tomultiple receivers. Concurrently, the group crypto may improvescalability of the system without compromising the security of thesystem. Further, by using crypto, the traffic is protected forconfidentiality, integrity, and anti-replay. In addition, PMUs 26 do nothave to deal with authentication of PMU data consumers 70.Authentication and authorization of traffic from PMUs 26 can be handledby another centralized system, which passes the group key to PMU dataconsumers 70 (i.e., end receivers), if they are authorized to viewtraffic from PMU 26.

In another example, IP source guard (IPSG) may be enabled on anuntrusted interface. IPSG is a security feature that can restrict IPtraffic on non-routed, Layer 2 interfaces by filtering traffic based onthe DHCP snooping binding database and/or on statically configured IPsource bindings. After IPSG is enabled on an interface, a switch canblock the IP traffic received on the interface, except for DHCP packetsallowed by DHCP snooping. A port ACL can be applied to the interface toallow only IP traffic with a source IP address in the IP source bindingtable (and deny other traffic). The port ACL can have precedence overrouter ACLs or VLAN maps that affect the same interface.

The IP source binding table bindings can be learned by DHCP snooping, orcan be manually configured (static IP source bindings). An entry in thistable has an IP address with its associated media access control (MAC)address and VLAN number. The switch uses the IP source binding tableonly when IP source guard is enabled. IPSG for static hosts extends theIPSG capability to non-DHCP and static environments. The previousexample of IPSG used the entries created by DHCP snooping to validatethe hosts connected to a switch. Any traffic received from a hostwithout a valid DHCP binding entry is dropped. This security featurerestricts IP traffic on non-routed Layer 2 interfaces, as the systemfilters traffic based on the DHCP snooping binding database and onmanually configured IP source bindings. The previous example of IPSGrequired a DHCP environment for IPSG to work.

IPSG for static hosts allows IPSG to work without DHCP. IPSG for statichosts can rely on IP device tracking table entries to install port ACLs.The switch can create static entries based on ARP requests, or other IPpackets, to maintain a list of valid hosts for a given port. The numberof hosts allowed to send traffic to a given port can also be specified.This can be thought of as the equivalent to port security at Layer 3.

IPSG for static hosts can also support dynamic hosts such that if adynamic host receives a DHCP-assigned IP address, which is available inthe IP DHCP snooping table, the same entry is learned by the IP devicetracking table. In a stacked environment, when a master failover occurs,the IP source guard entries for static hosts attached to member portscan be retained. IPSG for static hosts initially learns IP or MACbindings dynamically through an ACL-based snooping mechanism. IP or MACbindings can be learned from static hosts by ARP and IP packets.

The IP or MAC bindings are stored in a device-tracking database. Whenthe number of IP addresses that have been dynamically learned orstatically configured on a given port reaches a maximum, the hardwarecan drop any packet with a new IP address. To resolve hosts that havemoved (or gone away), IPSG for static hosts can leverage IP devicetracking to age out dynamically learned IP address bindings. Thisfeature can be used with DHCP snooping. Multiple bindings can beestablished on a port that is connected to both DHCP and static hosts.For example, bindings can be stored in both the device-trackingdatabase, as well as in the DHCP snooping binding database.

In another implementation, IP traffic is filtered based on the source IPand MAC addresses. The switch forwards traffic only when the source IPand MAC addresses match an entry in the IP source-binding table. Whenaddress filtering is enabled, a switch can filter IP and non-IP traffic.If the source MAC address of an IP or non-IP packet matches a valid IPsource binding, the switch forwards the packet. The switch can dropother types of packets, except DHCP packets. The switch can use portsecurity to filter source MAC addresses. The interface can shut downwhen a port-security violation occurs.

Secure MAC addresses can allow a maximum number of secure addresses on aport, which is configured using a switch port port-security maximumvalue interface configuration command. The switch may support staticsecure MAC addresses that are manually configured by using a switch portport-security MAC address or MAC address interface configurationcommand. The static secure MAC addresses are stored in the address tableand added to the switch (e.g., during configuration activities). Inaddition, the dynamic secure MAC addresses may be configured, storedonly in the address table, and removed when the switch restarts.Further, sticky secure MAC addresses can be dynamically learned ormanually configured, stored in the address table, and added to therunning configuration. If sticky secure MAC addresses are saved in theconfiguration file, when the switch restarts, the interface does notneed to dynamically reconfigure them.

An interface may be configured to convert the dynamic MAC addresses tosticky secure MAC addresses, and to add them to the runningconfiguration by enabling sticky learning. To enable sticky learning, aswitch port port-security MAC address sticky interface configurationcommand may be entered into the interface. When the command is entered,the interface converts the dynamic secure MAC addresses, including thosethat were dynamically learned before sticky learning was enabled, tosticky secure MAC addresses. Then the sticky secure MAC addresses areadded to the running configuration.

In certain implementations, the sticky secure MAC addresses do notautomatically become part of the configuration file, which is thestartup configuration used each time the switch restarts. If stickysecure MAC addresses are saved in the configuration file, when theswitch restarts, the interface does not need to relearn these addresses.The maximum number of secure MAC addresses that can be configured on aswitch stack can be set by the maximum number of available MAC addressesallowed in the system.

A security violation may occur if the maximum number of secure MACaddresses have been added to the address table, and a station whose MACaddress is not in the address table attempts to access the interface. Asecurity violation may also occur if an address learned or configured onone secure interface is seen on another secure interface in the sameVLAN. When a security violation does occur, remedial actions may betaken. For example, when the number of secure MAC addresses reaches themaximum limit allowed on the port, packets with unknown source addressesare dropped until a sufficient number of secure MAC addresses areremoved to drop below the maximum value. In another example, the numberof maximum allowable MAC addresses is increased. As a result, a simplenetwork management protocol (SNMP) trap can be sent, a syslog message islogged, and the violation counter would increment. Alternatively, thenumber of maximum allowable addresses may be increased.

In another implementation, a port security violation causes theinterface to become error-disabled, to shut down, and the port LED canturn off. An SNMP trap may then be sent, a syslog message logged, andthe violation counter is incremented. When a secure port is in theerror-disabled state, it can be brought out of this state by enteringthe error disabled (e.g., ‘errdisable’) recovery cause secure violationcommand (e.g., ‘psecure-violation’ global configuration command in thedefault mode). In an embodiment of the present disclosure, a virtual LAN(VLAN) can be error disabled instead of the entire port when a violationoccurs.

In another embodiment, packet filtering can help to limit networktraffic and restrict network use by certain users or certain devices.ACLs can filter traffic as it passes through a router (e.g., a first-hoprouter) or a switch and, further, permit or deny packets crossing onphysical interfaces or VLANs. An ACL is a sequential collection ofpermit and deny conditions that can apply to packets. When a packet isreceived on an interface, the switch is configured to compare the fieldsin the packet against any applied ACLs to verify that the packet has therequired permissions to be forwarded based on the criteria specified inthe access lists.

The switch is configured to test packets (e.g., individually) againstthe conditions in an access list. The first match decides whether theswitch accepts or rejects the packets. Because the switch stops testingafter the first match, the order of conditions in the list can becritical. If no conditions match, the switch can reject the packet. Ifthere are no restrictions, the switch can forward the packet; otherwise,the switch can drop the packet. The switch can use ACLs on packets itforwards including packets bridged within a VLAN.

Access lists can also be configured on a router or Layer 3 switch toprovide basic security for the network. If no ACLs are configured,packets passing through the switch could be allowed onto various partsof the network. ACLs can be used to control which hosts can accessdifferent parts of a network, or to decide which types of traffic areforwarded or blocked at router interfaces. ACLs can also be configuredto block inbound traffic, outbound traffic, or both. An ACL may includean ordered list of access control entries (ACEs). Each ACE specifies“permit” or “deny” and a set of conditions the packet should satisfy inorder to match the ACE. The meaning of permit or deny depends on thecontext in which the ACL is used. The switch can support IP ACLs andEthernet (MAC) ACLs: IP ACLs filter IPv4/IPv6 traffic, including TCP,User Datagram Protocol (UDP), Internet Group Management Protocol (IGMP),and Internet Control Message Protocol (ICMP), etc. The switch may alsosupport QoS classification ACLs.

In one implementation, after a MAC ACL is created, the MAC ACL can beapplied to a Layer 2 interface to filter non-IP traffic propagating tothat interface. If the ACL is applied to a Layer 2 interface that is amember of a VLAN, the Layer 2 (port) ACL can have precedence over aninput Layer 3 ACL (applied to the VLAN interface, or a VLAN map appliedto the VLAN). Incoming packets received on the Layer 2 port can befiltered by the port ACL. A single IP access list and MAC access listshould be applied to the same Layer 2 interface. The IP access list canfilter IP packets, and the MAC access list filters non-IP packets. ALayer 2 interface can have one MAC access list. If a MAC access list isapplied to a Layer 2 interface that has a MAC ACL configured, the newACL replaces the previously configured one.

Note that in certain example implementations, the grid management and/orcommunication functions outlined herein may be implemented by logicencoded in one or more tangible media (e.g., embedded logic provided inan application specific integrated circuit [ASIC], digital signalprocessor [DSP] instructions, software [potentially inclusive of objectcode and source code] to be executed by a processor, or other similarmachine, etc.). In some of these instances, a memory element [as shownin FIGS. 2A, 2B, and 3A] can store data used for the operationsdescribed herein. This includes the memory element being able to storenon-transitory code (e.g., software, logic, processor instructions,etc.) that is executed to carry out the activities described in thisSpecification. A processor can execute any type of instructionsassociated with the data to achieve the operations detailed herein inthis Specification. In one example, the processor [as shown in FIGS. 2A,2B, and 3A] could transform an element or an article (e.g., data) fromone state or thing to another state or thing. In another example, theactivities outlined herein may be implemented with fixed logic orprogrammable logic (e.g., software/computer instructions executed by aprocessor) and the elements identified herein could be some type of aprogrammable processor, programmable digital logic (e.g., a fieldprogrammable gate array [FPGA], an erasable programmable read onlymemory (EPROM), an electrically erasable programmable ROM (EEPROM)) oran ASIC that includes digital logic, software, code, electronicinstructions, or any suitable combination thereof.

In regards to the infrastructure of grid system 10, in one exampleimplementation, PMU 26, PDC 28, FHR 32, LHR 64, PMU data consumer 70,and/or service module 92 are simply reflective of a network elementconfigured for conducting the energy management activities discussedherein. As used herein in this Specification, the term ‘network element’is meant to encompass first-hop routers/last-hop routers, servicedevices, servers, consoles, network appliances, proprietary devices,switches, gateways, bridges, loadbalancers, firewalls, sensors (of anykind), inline service nodes, proxies, processors, modules, or any othersuitable device, component, element, or object operable to exchangeinformation in a network environment. This network element may includeany suitable hardware, software, components, modules, interfaces, orobjects that facilitate the operations thereof. This may be inclusive ofappropriate algorithms and communication protocols that allow for theeffective exchange (reception and/or transmission) of data orinformation.

Additionally, PMU 26, PDC 28, FHR 32, LHR 64, PMU data consumer 70,and/or service module 92 may include software (e.g., unicast tomulticast module 86) in order to achieve the grid management and/orcommunication functions outlined herein. These devices may further keepinformation in any suitable memory element [random access memory (RAM),ROM, EPROM, EEPROM, ASIC, etc.], software, hardware, or in any othersuitable component, device, element, or object where appropriate andbased on particular needs. Any of the memory items discussed herein(e.g., database, tables, trees, cache, etc.) should be construed asbeing encompassed within the broad term ‘memory element.’ Similarly, anyof the potential processing elements, modules, and machines described inthis Specification should be construed as being encompassed within thebroad term ‘processor.’ Each of these elements can also include suitableinterfaces for receiving, transmitting, and/or otherwise communicatingdata or information in a network environment.

Note that with the example provided above, as well as numerous otherexamples provided herein, interaction may be described in terms of two,three, or four network elements. However, this has been done forpurposes of clarity and example only. In certain cases, it may be easierto describe one or more of the functionalities of a given set of flowsby only referencing a limited number of network elements. It should beappreciated that grid system 10 (and its teachings) are readily scalableand can accommodate a large number of components, as well as morecomplicated/sophisticated arrangements and configurations. Accordingly,the examples provided should not limit the scope or inhibit the broadteachings of grid system 10 as potentially applied to a myriad of otherarchitectures.

It is also important to note that the steps in the preceding flowdiagrams illustrate only some of the possible scenarios and patternsthat may be executed by, or within, grid system 10. Some of these stepsmay be deleted or removed where appropriate, or these steps may bemodified or changed considerably without departing from the scope of thepresent disclosure. In addition, a number of these operations may havebeen described as being executed concurrently with, or in parallel to,one or more additional operations. However, the timing of theseoperations may be altered considerably. The preceding operational flowshave been offered for purposes of example and discussion. Substantialflexibility is provided by grid system 10 in that any suitablearrangements, chronologies, configurations, and timing mechanisms may beprovided without departing from the teachings of the present disclosure.

In addition, although the PMU data management activities discussedherein have been described as being applied at the transmission level,such activities could readily be implemented at the distribution levelwithout departing from the broad scope of the present disclosure.Moreover, any type of sensor (not only PMUs/PDCs, etc.) could beaccommodated in the context of the data management activities discussedherein.

In order to assist the United States Patent and Trademark Office (USPTO)and, additionally, any readers of any patent issued on this applicationin interpreting the claims appended hereto, Applicant wishes to notethat the Applicant: (a) does not intend any of the appended claims toinvoke paragraph six (6) of 35 U.S.C. section 112 as it exists on thedate of the filing hereof unless the words “means for” or “step for” arespecifically used in the particular claims; and (b) does not intend, byany statement in the specification, to limit this disclosure in any waythat is not otherwise reflected in the appended claims.

1.-20. (canceled)
 21. A method, comprising: determining a plurality ofservices to be performed on phasor measurement unit (PMU) data;identifying a plurality of service devices, wherein each of theplurality of service devices is to perform one or more of the pluralityof services on the PMU data; and directing the PMU data across theplurality of service devices to perform the plurality of services on thePMU data.
 22. The method of claim 21, further comprising: classifyingthe PMU data via a service insertion architecture (SIA) protocol todetermine a service classification for the PMU data.
 23. The method ofclaim 22, further comprising: appending one or more packets of the PMUdata with the service classification.
 24. The method of claim 23,wherein the appending further comprises including the serviceclassification within an SIA context associated with the one or morepackets of the PMU data.
 25. The method of claim 24, further comprising:receiving at least one packet of PMU data appended with the SIA context;identifying the service classification for the at least one packet ofPMU data via the SIA context; determining a service policy for the atleast packet of PMU data based, at least in part, on the serviceclassification; and applying the service policy to the at least onepacket of PMU data.
 26. The method of claim 25, further comprising:determining a service device to receive the at least one packet of PMUdata based, at least in part, on the SIA context; and communicating theat least one packet of PMU data to the service device.
 27. The method ofclaim 25, further comprising: removing the SIA context from the at leastone packet of PMU data if a last service is performed on the at leastone packet of PMU data.
 28. Logic encoded in one or more non-transitorymedia that includes code for execution that when executed by a processoris operable to perform operations, comprising: determining a pluralityof services to be performed on phasor measurement unit (PMU) data;identifying a plurality of service devices, wherein each of theplurality of service devices is to perform one or more of the pluralityof services on the PMU data; and directing the PMU data across theplurality of service devices to perform the plurality of services on thePMU data.
 29. The logic of claim 28, the operations further comprising:classifying the PMU data via a service insertion architecture (SIA)protocol to determine a service classification for the PMU data.
 30. Thelogic of claim 29, the operations further comprising: appending one ormore packets of the PMU data with the service classification.
 31. Thelogic of claim 30, wherein the appending further comprises including theservice classification within an SIA context associated with the one ormore packets of the PMU data.
 32. The logic of claim 31, the operationsfurther comprising: receiving at least one packet of PMU data appendedwith the SIA context; identifying the service classification for the atleast one packet of PMU data via the SIA context; determining a servicepolicy for the at least packet of PMU data based, at least in part, onthe service classification; and applying the service policy to the atleast one packet of PMU data.
 33. The logic of claim 32, the operationsfurther comprising: determining a service device to receive the at leastone packet of PMU data based, at least in part, on the SIA context; andcommunicating the at least one packet of PMU data to the service device.34. The logic of claim 32, the operations further comprising: removingthe SIA context from the at least one packet of PMU data if a lastservice is performed on the at least one packet of PMU data.
 35. Anapparatus, comprising: a memory element configured to store data; aprocessor operable to execute instructions associated with the data,wherein the apparatus is configured for: determining a plurality ofservices to be performed on phasor measurement unit (PMU) data;identifying a plurality of service devices, wherein each of theplurality of service devices is to perform one or more of the pluralityof services on the PMU data; and directing the PMU data across theplurality of service devices to perform the plurality of services on thePMU data.
 36. The apparatus of claim 35, wherein the apparatus isfurther configured for: classifying the PMU data via a service insertionarchitecture (SIA) protocol to determine a service classification forthe PMU data.
 37. The apparatus of claim 36, wherein the apparatus isfurther configured for: appending one or more packets of the PMU datawith the service classification.
 38. The apparatus of claim 37, whereinthe appending further comprises including the service classificationwithin an SIA context associated with the one or more packets of the PMUdata.
 39. The apparatus of claim 38, wherein the apparatus is furtherconfigured for: receiving at least one packet of PMU data appended withthe SIA context; identifying the service classification for the at leastone packet of PMU data via the SIA context; determining a service policyfor the at least packet of PMU data based, at least in part, on theservice classification; and applying the service policy to the at leastone packet of PMU data.
 40. The apparatus of claim 39, wherein theapparatus is further configured for: determining a service device toreceive the at least one packet of PMU data based, at least in part, onthe SIA context; and communicating the at least one packet of PMU datato the service device.